PROJECT SUMMARY Emerging evidence suggests that the post-transcriptional messenger RNA (mRNA) modification N6- methyladenosine (m6A) is a fundamental mRNA regulatory mechanism. This modification tags thousands of mRNAs and regulates their activities through diverse mechanisms. Phenotypes seen following knockout of m6A methyltransferases in mouse or human neural stem cells (NSCs) support the idea that the modification is required for proper NSC activity and for brain development. We recently discovered crosstalk between m6A and histone post-transcriptional modifications (PTMs) in NSCs. Specifically, we reported a dual function of m6A in regulating both active and repressive histone PTMs, and showed that these histone PTMs target different functional classes of NSC genes to keep NSCs at ground state. In this application, we continue to use NSCs as a model system in order to investigate molecular mechanisms underlying m6A regulation of histone PTMs. We will ask whether m6A modulates expression of histone-modifying enzymes (Aim 1), or regulates binding of histone-modifying enzymes to RNA and/or chromatin (Aim 2). This work will guide future investigation of interactions between RNA- and histone- modifications. In addition, since m6A mRNA modification represents a fundamental gene regulatory mechanism in development and is perturbed in some human neurological diseases and cancers, mechanistic analysis of m6A function could significantly advance our understanding of normal development and provide a basis for future investigation of m6A dysregulation in human diseases.